Method of controlling product volume in a fixed volume mold

ABSTRACT

A method for precisely controlling the volume of a product such as a tire tread or tire that is placed into a mold is provided. This method includes providing a tread or tire that is built upon a portable mold core by laying a series of layers on the portable mold core. The outer diameter of the tire tread or tire is initially built to be purposely smaller than the interior surfaces of the mold in order to prevent any interference from occurring between the mold and the tire tread once the tire tread and core are placed within the mold and the mold is closed. The weight of the tire tread or tire is measured to see if the volume of the tire tread or tire is within acceptable parameters to fit within the mold. If not, additional material is added to the tire or tire tread.

This application is a continuation of application Ser. No. 13/510,713,filed May 18, 2012, which was a nationalization of PCT Application No.PCT/US2009/066039, filed Nov. 30, 2009, each which are herebyincorporated by reference in their entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates generally to a method of manufacturing tires thatare cured in a mold, and, more specifically, to a method for fabricatinga tire or tire tread around a portable mold core, both of which aremoved through various tire building stages until the tire or tire treadand core are placed into a mold where the rubber materials of the tireare cured.

2. Description of the Related Art

It is commonly known that tires are made by wrapping a number of tireproducts including carcass plies, belts and tread rubber sequentiallyabout a building drum or other apparatus that provides a buildingsurface. Many of these products include a rubber or some other thermosetelastomer in them that is in the “green” or uncured state during thetire building process. It is desirable that these materials be curedafter the tire has been built so that their molecules cross link, whichimparts them with greater durability which is particularly advantageousin promoting the endurance and life of the tire in use. In order toaccomplish this, the green tire is typically placed into a mold wheresufficient heat and pressure are added to the rubber and elastomermaterials so that curing or vulcanization occurs, creating the crosslinked molecules that provide the aforementioned desirablecharacteristics.

Pneumatic tires also have sidewalls that terminate in bead sections, allof which are built onto the building drum, and that provide the means bywhich the tire is held onto the rim of a vehicle. This type of tire isoften cured in a mold whose surfaces that form the outer portions of thetire, including the width of the tire and its outer circumference, whichare spatially fixed and that also has an inflatable bladder that mateswith the inner surfaces of the tire. As can be imagined, the volume oftires placed into such a mold varies as a result of the tire buildingprocess as the tire products are laid onto the building drum. This isattributed to slight mass variations within the products that make upthe tire as well as the imprecision with which these products are placedon top of each other. Also, there are usually tiny air pockets that havebeen trapped during the fabrication of the tire as one layer is laidupon another. Once a green tire is placed into the mold, the inflatablebladder is expanded with enough pressure so that any gaps between thefixed surfaces of the mold and the outer surfaces of the tire as well asany air pockets within the tire itself are removed, helping to ensurethat heat and pressure can be effectively transferred to the rubbermaterials for proper vulcanization. The typical industry practiceresults in a situation where an uncured tire is often smaller than thevolume of the closed mold and that this design criteria accounts for anycustomary building product volume variation. When the uncured tire issmaller than the closed mold volume, the mold can be closed viaconventional tire curing press technology. The inflation bladderexpansion accommodates any normal volume variations that occur fromuncured tire to uncured tire during production. Further, shouldconditions result in uncured tires that are oversized as compared to thevolume of the mold, the pressure within the inflatable bladder, and itsflexibility, allow the mold to close properly, without damage to themold itself or the surrounding mechanisms. Once the mold is fully closedand locked, the inflatable bladder is then expanded so that properconduction of heat and pressure from the mold to the tire can beachieved as previously described.

However, such molding technology does not work effectively with alltypes of tires. For example, some non-pneumatic tires have a shear bandin their tread that comprises inextensible membranes that surround ashear layer made of an elastomer material. For an example of thisconstruction, see U.S. Pat. Nos. 6,769,465; 7,013,939 and 7,201,194 thatare commonly owned by the assignee of the present application. Themembranes are very stiff, i.e. 100 to 1000 times more stiff than rubber,as they often use reinforcements made of uninterrupted steel cord.Further, the orientation of the reinforcements within the membranes isgenerally circumferential. The combined result of reinforcement andorientation is the inextensible nature of these membranes. This isdifferent from typical pneumatic tire industry practice, where the steelcords are angled with respect to the circumference of the tire belts.The presence of this cord angle introduces interruptions of the cordalong the circumferential direction of the belts. These interruptions ofthe steel cords, along with the low stiffness circumferentialreinforcements that are also in typical use by the tire industry, resultin uncured pneumatic tires that are extensible in circumference andtherefore are compatible with inflatable bladder molding technology.

When inflatable bladders are used with tire constructions that includeinextensible membranes, one of two adverse reactions generally occur.When there is insufficient uncured tire volume, the inflatable bladderwill force an undesirable flow of rubber between the steel cords, whichdegrades the mechanical performance of the cured tire. Conversely, whenthere is excess uncured tire volume, the closing mold will distort thebelts as the tire is forced to have a smaller circumference. Theinextensible belts must buckle, since they cannot change circumference.The inflatable bladders, lacking any mechanism to constrain distortion,simply accommodate the buckling and thus allow the distortion to becomea permanent feature of the cured tire.

Accordingly, it is desirable to find a method for controlling the volumeof the tire tread or tire precisely so that it can fit snugly within amold without damaging the tire tread or tire, or other componentsthereof, upon mold closing and so that the tread or tire expandssufficiently as the mold heats up so that it contacts the mold withoutcausing the flow of rubber between the steel cords of an inextensiblemembrane, helping to ensure that enough pressure and heat aretransferred to the elastomer materials in the tread or tire for propervulcanization and the removal of any air pockets found within the treador tire.

SUMMARY OF THE INVENTION

Particular embodiments of the present include a method for controllingthe volume of a product that is placed in a mold comprising thefollowing steps. A mold and portable mold core are provided. One or morelayers of products are laid onto the portable mold core to form a tireor tire tread. The tire or tire tread is weighed. If the weight of thetire or tire tread is within acceptable parameters, the tire or tiretread and the portable mold core are placed into a mold.

In certain cases, the method further comprises the step of addingmaterial to the tire or tire tread if after weighing the tire or tiretread the weight of the tire or tire tread as calculated is not withinacceptable parameters. This step of adding material to the tire or tiretread may include adding a strip of material to the outer circumferenceof the tire or tire tread that is spaced approximately 75 millimetersaway from a side surface of the tire or tire tread. In still othercases, the step of adding material also includes adding a second stripof material to the outer circumference of the tire or tire tread that isspaced 75 millimeters away from the other side surface of the tread ortire. The first and second strips of material may be made from amaterial that is compatible with the top layer of the tire tread and mayhave the same dimensions as each other. In such a situation, thethickness and width of the strips of material are approximately 2millimeters and 30-40 millimeters respectively. Also, the strips ofmaterial may be wound completely around the circumference of the tiretread. In some cases, one or more strips of rubber are stretched as theyare applied to the tread or tire to adjust the amount of weight that isadded to the tire or tread.

In other embodiments, the method may further comprise the step ofreweighing the tire or tire tread and determining whether the weight orvolume of the tire or tire tread is within acceptable parameters. Insome cases, the targeted mass that is equivalent to an acceptable volumefor the tire tread or tire ranges from approximately 58.3 to 59.4 Kg.The initial tire tread or tire may be built to be less than targetedmass and volume and may be within 99.1 and 100% of the targeted mass andvolume for the tire tread or tire.

Sometimes, the step of adding material leaves a void in at least oneplace between the mold and the circumference of the tire or tire tread,allowing the added material to flow into this void during the moldingprocess.

The method may further comprise the step of providing a core rotationspindle assembly to which the portable mold core is attached during theweighing step. In some cases, the core rotation spindle assemblyincludes a multi-sensor piezoelectric load plate subassembly that isused to weigh the tire tread or tire during the weighing step. In somecases, the method may further include the step of weighing each layer ofproduct as it is laid onto the portable mold core.

In still other embodiments, the method may further comprise the steps ofattaching the portable mold core to the core rotation spindle beforelaying down layers of products to form the tire tread or tire, movingthe core and spindle to various tire building stations and detaching theportable mold core and the tire tread or tire that has been builtthereon from the spindle and placing the portable mold core and tiretread or tire into a mold.

Sometimes this method further includes the step of preheating the moldcore, taring the spindle assembly before the mold core is attachedthereto for building the tire or tread and weighing the mold coreitself. It may also include the steps of removing the mold core afterthe tire or tread has been built on the mold core and compensating fortemperature drift of the spindle assembly. The step of compensating fortemperature drift of the spindle assembly may occur either before orafter the tire or tread have been removed from the spindle assembly.After this, the method may further include the steps of weighing themold core and tire tread together as an assembly and calculating howmuch material is needed to be added to the tire tread to reach thetarget weight by subtracting the weight of the mold core by itself.

In some cases where the target weight for the tire or tread has not beenreached, the method may further comprise the steps of adding morematerial to the tread or tire; compensating for the temperature drift ofthe spindle assembly; removing the mold core and tire or tread from thespindle assembly; recording the negative weight of the mold core andtire or tread; and calculating the weight of the tread or tire by takingthe negative value of the weight of the mold core and tire or tread justmeasured and subtracting the weight of the mold core itself.

The foregoing and other objects, features and advantages of theinvention will be apparent from the following more detailed descriptionsof particular embodiments of the invention, as illustrated in theaccompanying drawing wherein like reference numbers represent like partsof the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an environmental view showing the portable mold core, tirebuilding stations and core rotation spindle assembly of the presentinvention with the portable mold core and tread shown in a firstposition where they are attached to the spindle assembly for adding morerubber to the tread and in a second position where they have beeninserted into a mold;

FIG. 2 is a flow chart showing the steps of a method according to thepresent invention including the steps of taring the core rotationspindle assembly, compensating for the temperature drift of the spindleassembly, and weighing the portable mold core and tire tread;

FIG. 3 is front view of the core rotation spindle assembly of thepresent invention with the four sensor piezoelectric load platesubassembly shown with the portable mold core removed for clarity;

FIG. 4 is a perspective view of the tire tread being built on theportable mold core with the spindle assembly and indexer removed forenhanced clarity;

FIG. 5 is a front view of the portable mold core and tire tread showingadditional rubber being added to the tire tread in the form of twoelongated strips of rubber that are wound about the circumference of thetire tread;

FIG. 5A is an enlarged view taken from FIG. 5 to more clearly show theapplication of the rubber strips onto the tread;

FIG. 6 is partial cross-sectional view of the portable mold core andtire tread with added rubber that has been placed into a mold with smallgaps found between portions of the tread and interior surfaces of themold as the mold closes and the mold sectors move inward toward thecircumferential surface of the tread; and

FIG. 7 is a partial cross-sectional view of the portable mold core, tiretread and mold of FIG. 6 showing the completely filled mold cavity dueto the flowing of the added rubber during the molding process after themold has been completely closed.

DETAILED DESCRIPTION OF PARTICULAR EMBODIMENTS

Looking at FIG. 1, an apparatus for building a tire tread that has ashear band comprising a shear layer that is sandwiched by twoinextensible membranes, as exemplified in U.S. Pat. Nos. 6,769,465;7,013,939 and 7,201,194; is shown. Specifically, this apparatus includesa portable molding core 100 that is readily attachable and detachable toother tire building equipment such as a mold 102 that is found in amolding press 103, core rotation spindle assembly 104 that is part of anindexer 108, and a cooling station (not shown). The portable moldingcore 100 comprises a cylinder with a circumferential surface 106 uponwhich components of the tire or tread 116 are laid by the tire buildingstation 114 or material compensation station 118 as the mold core 100 isrotated by the spindle assembly 104 about its horizontal axis H-H. Themold core 100 and tread 116 are rotated by the indexer 108 about itsvertical axis V-V at the appropriate time so that they are locatedbefore the desired building station 114, 118. The molding core 100 alsohas means for heating and cooling the cylinder such as cartridge heatersand/or heating and cooling circuits through which heating and coolingmedia can be passed for transferring heat to and from the mold core 100.

In the beginning of the tire tread building process, which is depictedby the steps shown in FIG. 2, this mold core 100 may be preheated, whichcorresponds to step 200 of the flowchart. This may be accomplishedeither by relying on the residual heat stored in the mold coresubsequent to a molding cycle that has occurred in the mold or byheating it using a preheating station or magazine (not shown) thatsupplies electrical power to the cartridge heaters of the mold core 100.This step aids in the tread building process by increasing the tackbetween various tire components that are laid onto the mold core and themold core itself, helping to keep these components in place during thetire building process. Furthermore, the heating of the core adds heat tothe tread during the building process, which reduces the curing timenecessary in the mold later on, which improves the overall productivityof the tire building process.

However, preheating the mold core 100 presents some challengesconcerning measuring the weight of the tire tread itself due to the heattransfer from the mold core 100 to the spindle assembly 104 whichinduces some stress on the sensors used in the spindle assembly 104 tomeasure weight, therefore particular steps must be taken to tare andweigh the spindle assembly 104, mold core 100 and tire tread, which aredescribed hereafter to prevent erroneous measurements from being taken(see FIG. 2 for a flow chart showing these steps). As can be imagined,this problem is exacerbated by the amount of precision such as +/−0.1%with which the weight of a tire or tread must be measured to fit snuglywithin a mold cavity. Just before the preheated mold core is attached tothe spindle assembly 104, this assembly, which is attached to theindexer 108 via a four sensor piezoelectric load plate subassembly 110(see FIG. 3) is readied to receive the mold core 100 by first adjustingthe charge amp of the sensors 112 to an output of zero. For thisembodiment, the sensors used are commercially available pressuretransducers that are sold by KISTLER under model no. 9146B and areloaded in shear between a front plate 109 and a rear plate 111 that areattached to the rear of the spindle assembly 104. These sensors have acrystal in them, which is sensitive to loads that are applied to it sothat it produces a charge as a result of any force exerted on it.Dimensional changes and shifts of the rear and front plates 109, 111that are caused by weight or temperature drift; therefore, affect theoutput of these sensors such that temperature drift of the spindleassembly and load plate subassembly may compromise the accuracy of anyweight measurement made by the sensors.

The taring step corresponds to step 210 of the flow chart. Thiscompensates for the weight of the spindle assembly 104 itself so that noerror is introduced when weighing the tire tread later on. Then the moldcore 100 is attached to the core rotation spindle assembly 104 by meanscommonly known in the art and is then positioned by the rotation of theindexer 108 about a vertical axis V-V such that the mold core 100 isimmediately in front of the tire building station 114, which is theequipment that lays the tire components upon the circumference 106 ofthe mold core 100 as it rotates. This step is represented by step 220 inthe flow chart. Next, the weight of the mold core 100 by itself ismeasured and recorded as represented by step 230.

For this embodiment, this equipment 114 lays down the rubber and steelcords that form an inextensible membrane 115, which is part of the shearband of the tread as shown by FIG. 4. After the shear band has beenbuilt on the mold core 100 (step 240), the indexer 108 rotates the coreand tread so that they are in front of the material compensation station118 where the tread rubber is laid down. Then the mold core 100 and thetread 116 are removed from the spindle assembly 104 (step 250). Onceagain, the charge amp for the sensors 112 is adjusted to zero (step260). This is done to compensate for the heat transfer that has occurredfrom the mold core 100 to the spindle assembly 104 during the buildingof the tread 116 onto the mold core 100 as this causes additional stressdue to dimensional changes of the plates 109, 111 to be imposed onto thesensors 112 in addition to the weight of the mold core 100 and tread116, creating offset drift when trying to weigh these components. Afterthe charge amp has been zeroed once more, the mold core 100 and tread116 are placed back onto the spindle assembly 104 (step 270) at thematerial compensation station 118 when the weight of the mold core 100and tread 116 are weighed and recorded (step 280).

Then, the amount of weight to be added to the tread, W_(additional), iscalculated to get it within the targeted weight range, W_(target), whichcorresponds to an acceptable volume of product which will fit snuglywithin the mold 100. This is done by subtracting the weight of the tread116 and solid core 100, W_(tread+core), which have been just weighedtogether, from the target weight, W_(target), and adding back the weightof the mold core 100, W_(core) which was measured initially by itself instep 230. This calculation, which corresponds to step 290 of the flowchart, is represented by the following equation:W_(additional)=W_(target)−W_(tread+core)+W_(core). For this embodiment,the targeted mass ranges from 58.3 to 59.4 Kg which is equivalent to aweight range of 571-582.12 N and 100-100.3% of the volume of the moldcavity. If the weight of the tire tread is within this range, then thetire tread is ready to be inserted into the mold. However, this israrely the case as the initial building of the tread is intentionallybuilt to be within 99.1 and 100% of the targeted mass so that the volumeof the tread is not larger than the mold can accommodate.

Alternatively, steps 250 and 270 of detaching and attaching the moldcore 100 and tread 116 to the spindle assembly 104 may be delayed soboth occur after step 260 which is the step of compensating fortemperature drift in the spindle assembly 104 by zeroing the charge ampfor the sensors 112. In this case, step 260 happens first and then themold core 100 and tread 116 are removed and the weight of the tread andcore having a negative value, −W_(tread+core), is measured and recorded.Then the weight to be added to the tread, W_(additional), is calculatedby adding the negative weight of the tread and core to the targetweight, W_(target), and adding the weight of the core, W_(core). Thiscalculation is represented by the following equation:W_(additional)=W_(target)+(−W_(tread+core))+W_(core). Assuming that theweight of the tread 116 is not within the targeted range, the mold core100 and tread 116 are reattached to the spindle assembly 104.

In such a case, more tread rubber must be added to the tire tread 116(step 300). The amount of additional rubber that needs to be added isthe weight that has just been calculated, W_(additional). The indexer108 rotates, positioning the mold core 100 and tread 116 so that theyare located in front of the material compensation station 118, which isthe equipment that adds the additional rubber onto the surface of thetread 116 that is compatible with the tread rubber. This station 118adds the rubber in increments so that the desired volume and mass of thetread 116 can be built slowly without overshooting these targets. Theamount of rubber necessary to be added is calculated based onW_(additional) in conjunction with the density of the tread rubber.

For this embodiment of the invention as shown by FIGS. 5 and 5A, thisstation 118 adds two strips 120 of thin rubber that are spaced D₁ from aside surface 122 of the tread 116 and are evenly spaced from theequatorial plane E-E of the tread 116, which is the plane that splitsthe tread 116 in half and that is perpendicular to the axis of rotationH-H of the spindle assembly 104. This distance D₁ is 75 mm but may haveother values that will allow a complete tread profile to be created inthe molding process as will be described later. Also, the tread 116 hasan overall width, OW, which is 315 mm for this embodiment of the tread116 but could be altered depending on the application. The strips 120 ofrubber have a thickness T and a width W, which are approximately 2 mmand 30-40 mm respectively for this embodiment but may have other valuesthat allow a complete tread profile to be created during the moldingprocess. These strips 120 are wound about the circumference 126 of thetire tread 116, which has a diameter, Dia, which is 825 mm for thisembodiment but could be altered depending on the application. In somesituations, the rate at which the strips 120 are applied to the tire ortread and the rate the spindle assembly 104 rotates are different,causing the strips 120 to be stretched, thereby adjusting the amount ofweight being added to the tire or tread.

After the additional strips of rubber have been added, the charge ampfor the sensors 112 is zeroed once more (step 310) to compensate forfurther temperature drift of the spindle assembly 104. The mold core 100and tire tread 116 are then removed from the spindle assembly 104 and anegative weight measurement of the mold core and tire tread after thecompensation, −W_(adj(tread+core)), is recorded (step 320). The finalweight of the tread, W_(final), is calculated during step 330 by takingthe negative value of this negative measurement and subtracting theweight of the mold core itself W_(core) (as calculated during step 230).This calculation is represented by the following equation:W_(final)=−(−W_(adj(tread+core)))−W_(core). The weight of the tread ischecked again (step 340). If the tire tread is still too small, thesteps of adding more rubber at the material compensation station 118 andcalculating the final tread weight are repeated until the target weightis reached.

Once the tire tread has been weighed and its weight is within thetargeted range, the tire tread 116 and mold core 100 are placed into themold 102 (step 350) by robotic or conveyor means. The mold 102 hasmovable sectors or side actions 124 that create the relief of thesculpture of the tread. They move in as the mold 102 vertically closes.Both movements occur by means commonly known in the art causing thesectors 124 to impinge upon the circumferential surface 126 of the treadto form the relief of the sculpture. As mentioned previously, the addedstrips 120 of rubber make the tire slightly larger than the cavity ofthe mold in certain areas, which necessarily means that these strips 120of rubber are compressed as the sectors 124 of the mold 102 move in asthe mold closes as shown by FIG. 6. This creates voids 128 between thetire tread 116 and the interior surfaces 130 of the mold 102 in otherareas. The compression of the mold sectors 124 against the added strips120 of rubber causes the sides 121 of the strips 120 of rubber to bulgeand expand. As a result, some flashing can occur into the seams foundbetween the individual mold sectors 124 as these strips 120 expand.Then, as heat and pressure are conveyed to the tire tread 116 by themold 102 and the portable mold core 100, the added strips 120 of rubberwill flow into the voids 128 found between the tire tread 116 and theinterior surfaces 130 of the mold 102, thereby creating a tire tread 116that has completely filled the cavity of the mold 102 as shown by FIG.7, which in turn results in a complete sculpture of the tire tread 116once the molding process is completed.

It should be noted that the mold 102 does not have an inflatable bladderthat is commonly used in tire molds. Instead, the portable mold core100, which has an outer ring 125 that is connected to an inner ring 127by pins 129 that allow the outer ring to expand and contract withchanges in temperature, is seated onto the exposed surface of the mold102 and centered therewith. In addition, the mold core 100 has heatingcartridges that connect to the mold 102 and receive power from the mold102, causing the mold core 100 to heat up. This in turn causes the outerring 125 of the mold core 100 to expand by an amount Δ (see FIG. 7) andsupply the necessary pressure and heat to the tire tread 116 as it iscompressed between the interior surfaces 130 of the mold 102 and thecircumferential surface 106 of the mold core 100. For this particularembodiment, Δ can range from 0.8-2.5 mm to provide the necessarycompression so that the tread 116 can be properly vulcanized and so thatany trapped air or gas bubbles found within it can escape.

Once the tread has been in the mold long enough for vulcanization tohave occurred, the mold is opened and the portable mold core and thetire tread are moved to a cooling station or extraction station wherethe mold core is placed on an exposed surface of the cooling station(not shown). At this time, the mold core is quickly cooled until itbegins to shrink while the diameter of the tread band remainssubstantially the same as the steel in shear band resists dimensionalchange. Consequently, a gap is created between the tread band and theportable mold core. The tread is then removed from the mold core by astripper ring found on the cooling station, which raises the tread untilthe tread is found above the mold core.

For this embodiment, the tread is now ready to have spokes added to thetread for connecting the tire as a whole to the rim of a vehicle. Thisis done by placing the tread into another mold (not shown) where thespokes are formed by pouring polyurethane into the mold. Once the spokesof the tire are cured and attached to the tread, the tire as a whole isready for use. At about the same time, the mold core is eitherreattached to the spindle assembly in order to build another treadthereon or is connected to a preheating station or magazine aspreviously described. Thus, the tire building process is begun oncemore.

While only a tread that is formed with spokes that is part of anon-pnuematic tire has been specifically described herein, it iscontemplated that this process could be used with tires that have othermeans for connecting the tread to the rim of vehicle including thosethat have more conventional sidewalls and/or bead sections. Accordingly,these other types of tires fall within the scope of the presentinvention.

While this invention has been described with reference to particularembodiments thereof, it shall be understood that such description is byway of illustration and not by way of limitation. For example, some ofthe equipment may be constructed and function differently than what hasbeen described herein and certain steps of the method may be omittedand/or performed in an order that is different than what has beenspecifically mentioned. Accordingly, the scope and content of theinvention are to be defined only by the terms of the appended claims.

What is claimed:
 1. A method for controlling the volume of a productthat is to be placed in a mold comprising: providing a mold and aportable mold core; providing a core rotation spindle assembly to whichthe portable mold core is attached during a weighing step, wherein thecore rotation spindle assembly includes a sensor subassembly that isused to weigh the tire tread or tire during the weighing step; attachingthe portable mold core to the core rotation spindle before laying downlayers of products to form the tire tread or tire, moving the core andspindle to various tire building stations; laying one or more layers ofproducts on the portable mold core to form a tire tread or tire;weighing the tire tread or tire by taring the core rotation spindle,detaching the core rotation spindle from the portable mold core anddetermining the weight of the tire tread or tire; and attaching the corerotation spindle to the portable mold core when the weight of the tiretread or tire is below acceptable parameters; and placing the tire treador tire and portable mold core into the mold when the weight of the tiretread or tire is within acceptable parameters.
 2. The method of claim 1,which further comprises adding material to the tire tread or tire whenafter weighing the tire tread or tire the weight of the tire tread ortire is not within acceptable parameters.
 3. The method of claim 2,wherein the step of adding material to the tire tread or tire comprisesadding a strip of material to the outer circumference of the tire treador tire that is spaced 75 millimeters away from a side surface of thetread or tire.
 4. The method of claim 3, wherein the thickness and widthof the strip of material added to the tire or tire tread is 2millimeters and 30-40 millimeters respectively.
 5. The method of claim4, wherein the strip of material is wound completely around thecircumference of the tire tread or tire.
 6. The method of claim 2,wherein the step of adding material leaves a void in at least one placebetween the mold and the circumference of the tire tread or tire,allowing the added material to flow into this void during the moldingprocess.
 7. The method of claim 1, wherein an initial tire tread or tireis intentionally built to be less than a targeted mass and volume forthe tire tread or tire.
 8. The method of claim 1, wherein the sensorsubassembly is a multi-sensor piezoelectric load plate subassembly. 9.The method of claim 1, which further comprises preheating the mold coreand taring the spindle assembly before the mold core is attached theretoand weighing the mold core once it is attached to the spindle assembly.10. The method of claim 9, which further comprises removing the moldcore after the tire tread or tire has been built thereon andcompensating for temperature drift of the spindle assembly, said step ofcompensating for the temperature drift of the spindle assembly occurringeither before or after the mold core and tire tread or tire have beenremoved from the spindle assembly.
 11. The method of claim 10, whichfurther comprises weighing the mold core and the tire tread together asan assembly and calculating how much material is needed to be added tothe tire tread-to reach the target weight by subtracting the weight ofthe mold core and the tire tread assembly from the target weight andadding the weight of the mold core by itself.
 12. The method of claim11, which further comprises adding more material to the tire tread ortire; compensating for the temperature drift of the spindle assembly;removing the mold core and tire tread or tire from the spindle assembly;recording the negative weight of the mold core and tire tread or tire;and calculating the weight of the tire tread or tire by taking thenegative of the value of the weight of the mold core and tire tread ortire just measured and subtracting the weight of the mold core byitself.
 13. The method of claim 2, wherein the step of adding materialincludes stretching a strip of material that is added to the tire treador tire to adjust the amount of weight that is added to the tire treador tire.